Vehicles, such as trucks or tractors for semis, are often provided with a bumper having a central or other opening to permit air to flow into lower regions of an engine compartment for cooling purposes. Also, such vehicles typically have a grille positioned over a large central opening at the front of the vehicle. The front grille opening is provided to allow the admission of air into the vehicle engine compartment for purposes such as providing engine cooling. Bug screens, which still permit the passage of air therethrough, are typically provided behind the grille opening.
These openings, although desirable for admitting air for engine cooling and other purposes, also add to the drag on the vehicle. That is, air enters such openings rather than being deflected along the aerodynamically contoured surfaces of the vehicle. The increased drag results in fuel usage inefficiencies (e.g., increased fuel consumption).